WASHINGTON - The Pirates continued to shuffle their infield for the first game of a series against the Washington Nationals Friday night as injuries required yet more manipulation.
Second baseman Neil Walker returned after missing the previous five games because of spasms in his lower back, but shortstop Jordy Mercer did not start because of continued tightness in his right forearm.
"I was hoping [Friday] I'd wake up and see improvement," Mercer said. "There's not improvement, but it's not any worse."
Josh Harrison played shortstop in Mercer's absence and Pedro Alvarez started his first game at third base since Aug. 2 after poor throws forced manager Clint Hurdle to make a change.
"As I said before, we'll find a game for him over there sooner or later and, the way things have played out, this is the way I chose to go and I think it makes the most sense for our club," Hurdle said. "We'll watch him, as we have, and I think if there's an opportunity with a lead late, there's a good chance that we might [substitute on] defense for him after his last at-bat."
Alvarez has practiced at first base in recent weeks, and Hurdle said Alvarez probably would have started a game at first this weekend if not for Mercer's injury. The other left-handed first baseman, Ike Davis, has taken Alvarez's work at first in stride.
"He shared advice with Pedro, as has Gaby [Sanchez]," Hurdle said. "Gaby's been through this a couple of times with us, new guys coming in and helping guys move into the infield. There hasn't been any push-back from anybody."
The Pirates and Alvarez have both said they consider him a third baseman; first base is a Band-Aid to get his bat in the lineup. Hurdle said Alvarez must prove his competence in a game to regain trust.
"We can work all we want on the side," Hurdle said. "It'll be the same thing when we get him over to first. You got to go deal with what you need to deal with. You got to roll up your sleeve and get your hands involved, and we're going to give him that opportunity [Friday]."
Pimentel goes on DL
The Pirates placed right-hander Stolmy Pimentel on the 15-day disabled list Friday, making a proactive move with the reliever's sprained right ankle to add John Axford to the active roster.
"With everything that's going on, we're probably a little aggressive," Hurdle said.
Pimentel said he hurt the ankle Wednesday night while making a pitch against the Detroit Tigers. Pimentel allowed three runs on two hits and two walks without recording an out.
"Whether it affected his outing, I don't know," Hurdle said. "We need some healthy arms and we need some healthy people."
Bill Brink: email@example.com and Twitter @BrinkPG.